Missouri Gov. Jay Nixon on Thursday rejected the calls of critics and said he wouldn’t replace a county prosecutor investigating a teen’s death in a police shooting almost two weeks ago.

Gov. Nixon said in television interviews broadcast Thursday that he wouldn’t remove St. Louis County Prosecuting Attorney Robert McCulloch, who had received petitions signed by thousands asking him to step aside and had criticized the governor for not declaring his support vigorously enough.

St. Louis County prosecutors on Wednesday began a week-long process of presenting evidence to a grand jury in the police shooting of an unarmed black teenager that has sparked unrest here.

Mr. McCulloch is turning to the 12-member grand jury to determine whether criminal charges should be filed in the death of Michael Brown, who was shot by Ferguson Police Officer Darren Wilson. The proceedings are secret.

Mr. McCulloch said two attorneys from his office are presenting the evidence to the grand jury. His office expects that the process could stretch into mid-October, but that is a rough estimate and there is no strict timetable.

In recent days, Mr. McCulloch has come under fire, with some calling for a special prosecutor to take over the case. A MoveOn.org online petition advocating for the change has garnered about 64,000 signatures. Organizers of the petition note a decision in 2000 by Mr. McCulloch not to charge officers in a police shooting that left two people dead.

Some critics also point to the death of Mr. McCulloch’s father, a St. Louis police officer who was killed by an armed suspect in 1964, as another reason he should step aside.

So not only are they refusing to remove this man as the lead investigator, he’s now conducting a “secret” investigation??? This is just another reason why we must all do what we can to continue seeking #JUSTICEFORMIKEBROWN